The invention relates to an installation for cooling hot, dust-charged gas in a steam generator, which consists of a first radiant heat exchanger and a second convection heat exchanger. In such installations the gas coming from the reactor is normally cooled in the radiant heat exchanger to a temperature below the softening point of the dust. When the gas enters into the convection heat exchanger, the dust particles are no longer sticky and can no longer become caked together on the effective heating surfaces of this heat exchanger. However the dust particles can become deposited in the tightly disposed heating surfaces of the convection heat exchanger and form blockages, so that the transfer of heat from the gas to the heating surfaces is impaired.